1. Field of the Invention.
The present invention is concerned with a device for regulating the flow of fluid in medical apparatus in which there is means for quickly adjusting the position of the flow regulating device.
2. Description of the Prior Art.
There are many applications of medical equipment in which it is necessary to adjust the flow of fluid. The adjusting means not only has to be relatively compact, but it is also highly desirable that it be capable of being adjusted quickly until the approximate flow regulating position is obtained, and thereafter adjusted very finely to obtain exactly the right adjustment. A typical application is in connection with intravenous feeding in which the fluid from a container designed to hold intravenous fluid is connected by a tube or other flexible conduit to means for introducing the fluid into the patient. Any means for regulating the flow of such fluid must be very compact and must be capable of quickly adjusting the flow of fluid. It also must be capable of adjusting it in very small increments so that the flow rate is exactly what is desired.
One way of adjusting flow of fluid in such apparatus is through the use of a conventional roller flow control clamp. This is referred to in the Dawe U.S. Pat. No. 4,432,762. The difficulty with this type of arrangement is that it is very difficult to effect accurate adjustment as there is a great tendency for the adjustment to shift once it has been set.
This problem is recognized in the McDonnell U.S. Pat. No. 3,841,354 in which there is a male member in threaded connection with a female member, the threads of the male member being less in height than the depth of the grooves in the female member so that there is a passage between the male and female members. McDonnell suggests varying the depth of the grooves to provide further adjustment. In such a case, the fluid travels helically in the space between the threads. McDonnell is specifically concerned with an arrangement for adjusting the flow of intravenous fluids. The McDonnell device is, however, of a type which requires relatively slow adjustment and, if one wishes to make a major adjustment of the rate of flow, it is necessary to move the valve member through a large number of turns.
In the fastener art, arrangements have been proposed for having a yieldable female member which permits the nut to be rapidly tightened until it is in its approximate position. Thereafter, the screw or cooperating nut are relatively rotated to tighten them up. A typical device of this type is shown in the Mizusawa U.S. Pat. No. 4,435,111. In this patent, there are thread-like members formed on three yieldable portions. These are formed in the nut and enable the nut to be quickly tightened. It is always possible, after the nut is in a relatively tight position, for additional tightening to be accomplished by relative turning of the nut and the bolt. There is no way, however, of quickly releasing the nut. It must be unscrewed as with a conventional nut. The threads are formed so that if an attempt is made to pull the nut off, the threads will not release. Furthermore, the arrangement of this patent is completely unsuitable for an arrangement such as a valve where it is necessary to seal against escape of fluid.
The Perry U.S. Pat. No. 2,926,409 shows a fastening device in which it is possible to pull the elements apart after they have been fastened. The device does not have screw threads, however, and there is no provision for fine adjustment.
The Gross U.S. Pat. No. 3,545,708 shows a fastner in which there is a yieldable member which engages helical threads of a stud. The device to which the yieldable member is attached can be withdrawn, particularly if the yieldable member is bent downwardly. There is no concept, however, of having fine threaded engagement.
The Iwata U.S. Pat. No. 4,299,520 shows another fastener in which it is possible to slip the nut on but in which it cannot be removed except by unthreading it.
None of the patents referred to above are expressly adapted to the use of a flow regulating device in which it is desired to quickly adjust the flow in either direction and thereafter to adjust it in small increments.